American Chemical Society
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Intensely Luminescent Alkynyl−Phosphine Gold(I)−Copper(I) Complexes: Synthesis, Characterization, Photophysical, and Computational Studies

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journal contribution
posted on 2009-03-02, 00:00 authored by Igor O. Koshevoy, Yi-Chih Lin, Antti J. Karttunen, Pi-Tai Chou, Pirjo Vainiotalo, Sergey P. Tunik, Matti Haukka, Tapani A. Pakkanen
The reactions between the diphosphino−alkynyl gold complexes (XC6H4C2Au)PR2−C6H4−PR2(AuC2C6H4X) with Cu+ lead to the formation of a family of heterometallic clusters of the general formula [{Au3Cu2(C2C6H4X)6}Au3(PR2C6H4PR2)3][PF6]2 (X = NO2, H, OMe, NMe2; R = C6H5, NC4H4). These complexes adopt the same structural pattern and consist of a heterometallic alkynyl cluster [Au3Cu2(C2C6H4X)6] “wrapped” by the cationic [Au3(PR2C6H4PR2)3]3+ “belt”. The novel compounds were characterized by NMR spectroscopy and ESI-MS measurements. A systematic study of their luminescence properties revealed efficient room-temperature phosphorescence in solution with remarkably weak quenching by molecular oxygen. The photophysical experiments demonstrate that the increase in the electron donor ability of the alkynyl ligands and the electron-withdrawing character of the diphosphines results in the bathochromic shift of emission maxima (in the 576−686 nm range) and a decrease in the luminescence quantum yield. The electronic structure calculations showed that variations of X or R substituents have very little effect on the structural parameters but display a significant influence on the electronic properties of the clusters and characteristics of luminescence. The metal-centered triplet emission within the heterometallic alkynyl cluster is suggested to play a key role in the observed phosphorescence.